Solar active region jets are small-scale collimated plasma eruptions that are triggered from magnetic sites embedded in sunspot penumbral regions. Multiple trigger mechanisms for recurrent jets are under debate. Vector magnetic field data from SDO-HMI observations are used to analyze a prolific photospheric configuration, identified in extreme ultraviolet observations as a `Coronal Geyser', that triggered a set of at least 10 recurrent solar active region jets. We focus on interpreting the magnetic fields of small-scale flaring sites aiming to understand the processes that govern recurrent jet eruptions. We perform a custom reprocessing of the SDO-HMI products, including disambiguation and uncertainty estimation. We scrutinized the configuration and dynamics of the photospheric magnetic structures. The magnetic configuration is described via the analysis of the photospheric magnetic vertical fields, to identify the process is responsible for driving the jet eruptions. We report that the two widely debated magnetic trigger processes, namely magnetic flux cancellation and magnetic flux emergence, appear to be responsible on a case by case basis for generating each eruption in our set. We find that 4 of 10 jets were due to flux cancellation while the rest were clearly not, and were more likely due to flux emergence.
We present observations of recurrent active region coronal jets and derive their thermal and non-thermal properties, by studying the physical properties of the plasma simultaneously at the base footpoint, and along the outflow of jets. The sample of analyzed solar jets were observed by SDO-AIA in Extreme Ultraviolet and by RHESSI in the X-Ray domain. The main thermal plasma physical parameters: temperature, density, energy flux contributions, etc. are calculated using multiple inversion techniques to obtain the differential emission measure from extreme-ultraviolet filtergrams. The underlying …
Coronal mass ejections (CMEs) and coronal jets are two types of common solar eruptive phenomena, which often independently happen at different spatial scales. In this work, we present a stereoscopic observation of a large-scale CME flux rope arising from an unwinding blowout jet in a multipolar complex magnetic system. Based on a multi-band observational analysis, we find that this whole event starts with a small filament whose eruption occurs at a coronal geyser site after a series of homologous jets. Aided by magnetic field extrapolations, it reveals that the coronal geyser site forms above …
Magnetic Flux Cancelation as the Trigger of Solar Coronal-Hole Coronal Jets
我们详细调查的磁原因的微灯丝喷发，驱动日冕洞射流。我们研究了13个随机的盘上冕洞喷流喷发，使用高分辨率的X射线图像从Hinode/XRT，EUV图像从SDO/AIA，和磁图从SDO/HMI。对于所有13个事件，我们跟踪的喷气基地区域的演变，并发现一个minifilament的冷（过渡区温度）等离子体是目前每个喷喷发之前。HMI磁图显示微丝沿着多数极性和少数极性磁通量贴片之间的磁中性线存在。这些斑块相互会聚和抵消，所有13个喷流的平均抵消率约为0.6 X 1018 Mx hr^{-1}。中性线上持续的通量抵消最终使微丝场不稳定，微丝场向外爆发并产生喷流尖顶。因此，我们发现，所有13个冕洞喷流驱动的微暗条爆发是由中性线上的通量抵消触发的。这些结果与Panesar et al 2016 b最近对平静区喷流的发现一致，其中底层中性线处的通量抵消触发了驱动每个喷流的微丝喷发。因此，通过对宁静太阳喷流和冕洞喷流研究，我们认为通量抵消是触发宁静区和冕洞喷流的主要候选者
Triggering process for prominence instability and consequent CMEs is not fully understood. Prominences are maintained by the Lorentz force against the gravity, therefore reduction of the prominence mass due to the coronal rain may cause the change of the force balance and hence destabilisation of the structures. We aim to study the observational evidence of the influence of coronal rain on the stability of prominence and subsequent eruption of CMEs. We used the simultaneous observations from AIA/SDO and SECCHI/STEREO spacecrafts from different angles to follow the dynamics of prominence/filame…
The triggering process for coronal mass ejections (CME) in the solar atmosphere is not fully understood. We use observations from different spacecraft at several wavelengths to detect an instability process for a prominence/filament with a subsequent eruption of CME. Time series of spectral lines at 304, 171, 193, and 211 Å have been obtained with the SDO spacecraft, and at 304, 171, 195, and 284 Å with the STEREO spacecraft. A prominence/filament system was observed during November 8-23, 2011, at different angles by SDO, STEREO_A, and STEREO_B. The observations show that a giant tornado began…
Many observations show that coronal holes (CHs) deviate coronal mass ejections (CMEs) away from them. However, there are some peculiar events reported where the opposite occurs. To contribute to a space weather forecast efforts, in relation to the prediction of CME trajectories, we study the interaction between flux ropes (FRs) and CHs through numerical simulations. We perform 2.5D numerical simulations where FRs and CHs interact with different relative polarity configurations. We also reconstruct the trajectory and magnetic environment of a peculiar event occurred on 30 April 2012. The numeri…
Solar coronal jets are frequently occurring collimated ejections of solar plasma, originating from magnetically mixed polarity locations on the Sun of size scale comparable to that of a supergranule. Many, if not most, coronal jets are produced by eruptions of small-scale filaments, or minifilaments, whose magnetic field reconnects both with itself and also with surrounding coronal field. There is evidence that minifilament eruptions are a scaled-down version of typical filament eruptions that produce solar flares and coronal mass ejections (CMEs). Moreover, the magnetic processes building up …
We present the sympathetic eruption of a standard and a blowout coronal jets originating from two adjacent coronal bright points (CBP1 and CBP2) in a polar coronal hole, using soft X-ray and extreme ultraviolet observations respectively taken by the Hinode and the Solar Dynamic Observatory. In the event, a collimated jet with obvious westward lateral motion firstly launched from CBP1, during which a small bright point appeared around CBP1's east end, and magnetic flux cancellation was observed within the eruption source region. Based on these characteristics, we interpret the observed jet as a…
Context: Many previous studies have shown that the magnetic precursor of a coronal mass ejection (CME) takes the form of a magnetic flux rope, and a subset of them have become known as `hot flux ropes' due to their emission signatures in $\sim$10 MK plasma. Aims: We seek to identify the processes by which these hot flux ropes form, with a view of developing our understanding of CMEs and thereby improving space weather forecasts. Methods: Extreme-ultraviolet observations were used to identify five pre-eruptive hot flux ropes in the solar corona and study how they evolved. Confined flares were o…
Observations of a Solar Jet Triggered by Reconnection between Super-penumbral Fibrils and a Mini-filament
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；East Coast Environmental Research Institute (ESERI), Universiti Sultan Zainal Abidin（苏丹扎因阿比丁大学东海岸环境研究所）
Context: In the context of the solar coronal heating problem, one possible explanation for the high coronal temperature is the release of energy by magnetohydrodynamic (MHD) waves. The energy transfer is believed to be possible, among others, by the development of the Kelvin-Helmholtz instability (KHI) in coronal loops. Aims: Our aim is to determine if standing slow waves in solar atmospheric structures such as coronal loops, and also prominence threads, sunspots, and pores, can trigger the KHI due to the oscillating shear flow at the structure's boundary. Methods: We used linearized nonstatio…
A single case study of a CBP in an equatorial coronal hole with an exceptionally large size is investigated to extend our understanding of the formation of mini-filaments, their destabilisation and the origin of the eruption triggering the formation of jet-like features recorded in the extreme-ultraviolet (EUV) and X-ray emission. We aim to explore the nature of the so-called micro-flares in CBPs associated with jets in coronal holes and mini coronal mass ejections in the quiet Sun. Co-observations from the Atmospheric Imaging Assembly (AIA) and Helioseismic Magnetic Imager (HMI) on board the …
Compact solar UV burst triggered in a magnetic field with a fan-spine topology
太阳紫外线爆发是小尺度的特征，表现出间歇性的增亮，被认为是由于磁重联。它们在色球层和过渡区，特别是在活跃区大量存在。我们详细研究了紫外线爆发有关的磁功能，是平流的护城河流从太阳黑子朝向孔。运动特征是寄生的，因为它的磁极性与斑点和孔隙的磁极性相反。我们利用IRIS的紫外光谱和狭缝颚观测来识别和研究上述紫外爆发的色球和过渡区光谱特征。为了研究紫外线爆发周围的磁拓扑结构，我们使用了两个小时长的时间序列的同时从HMI的视线磁图和数据驱动的三维磁场外推通过磁摩擦松弛技术。我们可以将紫外线爆发的特征与AIA观测到的覆盖在其上的EUV日冕环联系起来。紫外线爆发显示出各种各样的极宽的线轮廓，表明等离子体流量超过$\pm$ 200 km s $^{-1}$的时候。整个结构分为两个空间上不同的区域，主要是向上和向下流动。的磁场外推显示一个持久的风扇脊柱在紫外线爆发的磁拓扑结构。相关联的三维磁零点存在于光球上方约500公里的高度，并与观测到的紫外线爆发共空间演化。冕环足点的极紫外辐射与紫外爆发的演化密切相关。零点周围的磁场被光球运动剪切，触发磁重联，最终为观测到的紫外线爆发提供动力，并为覆盖在其上的日冕环提供能量。零点的位置表明爆发是在太阳色球层的低层触发的。
We present measurements of periodicity for transverse loop oscillations during the periods of activity of two remote and separated (both temporally and spatially) flares. The oscillations are observed in the same location more than 100 Mm away from the visible footpoints of the loops. Evidence for several possible excitation sources is presented. After close examination, we find that the eruptions during the flaring activities play an important role in triggering the oscillations. We investigate periodicities using time-distance, Fast Fourier Transform, and Wavelet techniques. Despite differen…
Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Excitation and evolution of oscillations in coronal loops is typically studied using highly idealised models of magnetic flux-tubes. In order to improve our understanding of coronal oscillations, it is necessary to consider the effect of realistic magnetic field topology and evolution. We study excitation and evolution of coronal oscillations in three-dimensional self-consistent simulations of solar atmosphere spann…
